Stabilized platform

ABSTRACT

A gyroscopically stabilized platform is provided with servo controls to eliminate gross pitch and roll motions of a ship on which the platform is mounted. The platform is fitted with gyroscopes which generate a voltage signal when the platform moves from its stabilized position. The voltage signal so produced is processed electronically in a control box wherefrom a signal is sent to servo valves which change hydraulic flow in an electro-hydraulic system of the platform. This change in hydraulic flow is such as to energize a group of actuators which command the platform back to the commanded stabilized position.

United States Patent White 1 May 21, 1974 [54] STABILIZED PLATFORM 3,531,998 10/1970 Warn et al. 74/534 [75] Inventor: Frederick W. White, North Franklin, Conn. Primary Exammer-Manuel A. Antonakas Attorney, Agent, or FirmRichard S. Sciascia; Arthur [73] Asslgnee: The United States of America as MCGi; prithvi G La represented by the Secretary of the Navy, Washlngton, DC. ABSTRACT [22] Filed: Dec. 4, 1972 A gyroscopically stabilized platform is provided with servo controls to eliminate gross pitch and roll motions of a ship on which the platform is mounted. The platform is fitted with gyroscopes which generate a [52] US. Cl 74/5.41, 74/522, 74/534 1 l h h l f f 51 Int. cl G01c 19/52 j l l f P P 5 581 Field of Search 74/5.22, 5.34, 54, 5.41 POsmon' e -"9 pm I cessed electronically in a control box wherefrom a siglis sent to servo valves which change hydraulic flow [56] References Cited I 1n an electro-hydraullc system of the platform. This UNITED STATES PATENTS change in hydraulic flow is such as to energize a group 3,456,51 l 7/1969 Clark et al. 74/5.4 of actuators which command the platform back to the Lynn X commanded tabilized osition 3,301,070 l/l967 Lapierre 74/5.4 p 3,068,705 12/1962 Tilly et al 74/54 5 Claims, 4 Drawing Figures ELEVATION OR states. were sells/1J1, OR RATE COMMAND ELECTRONICS SERVOVALVE ACTUATOR PQSmQN 0F CHAIR RATE GYRO STABILIZED PLATFORM STATEMENT OF GOVERNMENT INTEREST BACKGROUND OF THE INVENTION This invention relates to gyroscopically stabilized mechanisms and more particularly to a stabilized platform using an electro-hydraulic system.

In order to use a piece of equipment such as a telescope or binoculars to view a target from an observers position aboard a moving ship, it is necessary to stabilize the position of the equipment together with that of the observer, against motion of the ship. Purely mechanical systems employing springs and counterweights, to assure that the platform assumes a level position, have been devised. However, such systems do not compensate for motions of the foundation of the platform. Such systems prevent an accurate use of such equipment aboard a moving ship or an aircraft. Furthermore, an observer takes a longer time to gather target information because of instability resulting from the pitch and roll motions of the ship, whereas it is desirable to gather information about a target while aboard a moving ship as-quickly and as accurately as possible,

and to improve resolution of the target.

The objects and advantages of the present invention are accomplished by utilizing a gyroscopically stabilized platform which stabilizes the position of a piece of equipment and its operator aboard a moving ship. Such a stabilized platform comprises an electrohydraulic system which responds to any changes in position ofthe stabilized platform and thus to any changes in the position of an operator of the equipment and the equipment itself placed on the platofrm. The stabilized platform is commanded to a stabilized position by the operator in a certain elevation and bearing position. Any deviation in elevation or bearing of the platform generates a voltage signal which is fed to the first stage of the two-stage servo valve corresponding to the axis about which the platform has moved. The first stage of the servo valve is a torque motor that controls a jettype valve which in turn shifts the main spool of the valve. Thus the net result of platform motion is opening of the main spool of the servo valve to an amount proportional to the platform. motion. When the spool shifts, it directs oil into the proper actuator to bring the platform back to its original position. Both axes representing elevation and bearing operate independently so that the platform remains level in two planes corresponding to pitch and roll.

One object of this invention is to stabilize a person using a piece of equipment on a moving ship.

Another object of this invention is to have'a stabilizing mechanism for a platform which compensates motions of the platform foundation.

Still another object of this invention is to have a gyroscopically stabilized platform which uses an electrohydraulic system.

A further object of this invention is to allow the operator of an optical system aboard a moving ship to keep a target in field of view of the optical system and steady himself against the random motion of the ship.

Other'objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a stabilized platform showing a preferred embodiment of this invention;

FIG. 2 is a top view of the stabilized platform;

FIG. 3 is a cross-section of FIG. 1 taken along the line 3-3 of FIG. I; and

FIG. 4 is a block diagram of a preferred embodiment of the electro-hydraulic system of the invention.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings wherein like reference characters-designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, a side view of a stabilized platform in the form of a stabilized chair is shown. The stabilized chair consists essentially of a base or foundation 10 which has a mounting base 12 bolted thereon with bolts 14 and 16. A seat bracket 18 is mounted on mounting base 12 and a seat base 20 is attached to the seat bracket 18 by means of bolts 22 and 24 as shown in FIG. I. A chair 26 is attached to seat base 20 proximate end 28 of seat bracket 18. Control boxes 30 and 32 are also mounted on seat bracket 18 proximate the middle portion thereof. A fiber glass piece 34 is mounted around base 10 and'mounting base 12 and seat bracket 18 is attached to the fiber glass piece 34 as shown in FIGS. 1 and 2. A frame 36 comprising front rails 38 and side rails 40 and 42 and rear rail 44 is formed around the fiber glass piece 34. Frame 36 is secured to a seat adapter 45 at the front and to the seat bracket 18 at the rear. Foot rests 46 and 48 are provided for an operator sitting on chair 26. Foot rests 46 and 48 are secured to frame 36 as shown in FIGS. 1 and 2. A steel plate 50 is mounted next to seat bracket 18 on the front end thereof to provide stability to the frame 26. Electronic control boxes 30 and 32 house electronics circuitry including amplifiers, shapers and logic circuits, etc. Power to the electronic components in control box 32 and a signal path from rate gyros housed in a box 52 is carried by a cable 54 as shown in FIGS. I and 2-. Box

-52 also houses gyro drivers besides the rate gyro package for yaw and elevation. Cable 56 from control box 30 carries power to the electronic components in control box 30 and also carries signals to and from control box 30 Assembly 58 containing electronic hydraulic servo valve and electronic actuator controller for the elevation axis, and assembly '60 containing electronic hydraulic servo valve and electronicactuator controller for the yaw axis, are mounted on mounting base 12. Numeral 62 designates a yaw compensated swivel unit and numeral 64 represents yaw axis bearing as shown in FIG. 1. Equipment mount 66 is yaw and elevation compensated. A stand 68 is attached to equipment mount 66 for placing equipment 70, such as a telesocpe or binoculars, thereon. As shown in FIG. 3, rotary hydraulic acutators 74 nd 72 are installed for elevation and yaw lines respectively. Hydraulic manifold 76 is connected by hose 78 to a conventional hydraulic pump unit which feeds a suitable fluid, such as oil, to the manifold 76. Hose 79 is the return line from the manifold 76 tothe hydrauolic pump. Hoses 80 and 82 feed yaw axis rotary hydraulic actuator 72 and hoses 84 and 86 feed tubing 88 which feeds elevation axis rotary hydraulic actuator 74. Numerals 90 and 92 are limit switches for yaw axis and elevation axis respectively. Cable 94 provides power to the unit from a conventional power source. Sequence of events in the operation of the stabilized chair is shown in a block diagram form in FlG. 4.

OPERATION The'stabilized platform is commanded by the operator to be stabilized at a particular direction given by its azimuth and elevation.- If the platform moves from this position a voltage signal is-generated by gyroscopes in box 52 which is fed into control box 32 for electronic processing, The control box 32 thensends out a signal to the servo valves of assemblies 58 and 60 and the mand in. elevation 'or bearing is sent to control boxes 30 and 32 where it is processed electronically and the resulting signal therefrom is sent to electro-hydraulic servo valves of assembly 58 or assembly 60 which in turn actuates rotary hydraulic actuator 72 and 74. The rotary hydraulic actuators change the position of the chair 26. Any change in position of the chair26 energizes rate gyros housed in box 52 which produces a proportional electrical signal to be fed to control boxes 30 and 32 v Thus, an operator sitting on the chair with the chair in a stow position, the seat on deck and engaged in a stowing pin, turns on the main power switchlocated on the control box which turns on a small hydraulic pumping system located nearby and also applies power to the gryoscopes which start spinning. After a short delay the chair slowly swings out of the stow position by means of a small voltage applied to the valves by a logic contorl box. When the chair attains a desired elevation and azimuth. a ready light indicates to the operator that he I can now switch the gyroscopes on to the line" and stabilize at a selected direciton. This is done independently in elevation and azimuth. Switching to gyro stabilization is done by means of controls located on the control box front panel; if the operator then desires to move in elevation or azimuth while remaining in the gyro stabilized mode of operation, he can do so by manipulating the proper control switches to a new position and upon releasing these switches the chair is immediately stabilized at the new position. When the operator shuts the power off at the end of operation, the pump- 4 ing system continues to operate and the chair slowly swings back into the stow position, after which the hydraulic system is automatically turned off.

Obviously many modifications and variations of the present invention are possible in the light of above teachings. As an example, it is possible to use a twostage flapper-nozzle'type servo valve. Furthermore, it may be possible to changethe electro-hydraulic system by changing the number of servo valves and rotary hydraulic actuators used without deviating from the essence of this invention.

It is therefore understood that within the scope of the appended claims the invention may bepracticed otherwise than as specifically described. I

I claim:

1. A stabilized platform comprising:

a base assembly;

a stand mounted on said base assembly;

a plurality of rotary hydraulic actuators mounted on said base assembly;

a plurality of electro-hydraulic servo valves mounted on said base, each of said servo valves being connected to a corresponding hydraulic actuator of said plurality of rotary hydraulic actuators.

a plurality of rate gyros means, each of said gyro means being connected to a corresponding electrohydraulic servo valve of said plurality of servo valves;

electronic means for processing electrical signals from different members of said gyro means;

means for applying each of said electrical signals from each member of said plurality of rate gyro means to the corresponding electro-hydraulic servo valve to obtain an outputtherefrom;

means for applying the output of each of said plurality of electro-hydraulic servo valves to the corresponding rotary hydraulic actuator to obtain an output therefrom; and

means for controlling output of each of said plurality of gyro means by means of the output from the corresponding rotary hydraulic actuatorvand thereby affecting the position of said stand.

2. The platform of claim 1 wherein said electronic means further comprises a control and logic circuit.

3. The platform of claim 2 wherein each of the rate gyro-electrohydraulic servo valve'rotary hydraulic actuator combination has a limit switch incorporated therein.

4. The platform of claim 3 wherein eachof said electro-hydraulic servo valves is adapted to respond to low frequency changes in the position of said platform.

5. The platform of claim 4 wherein said electronic meansfurther includes amplifiers and shaper circuits. 

1. A stabilized platform comprising: a base assembly; a stand mounted on said base assembly; a plurality of rotary hydraulic actuators mounted on said base assembly; a plurality of electro-hydraulic servo valves mounted on said base, each of said servo valves being connected to a corresponding hydraulic actuator of said plurality of rotary hydraulic actuators. a plurality of rate gyros means, each of said gyro means being connected to a corresponding electro-hydraulic servo valve of said plurality of servo valves; electronic means for processing electrical signals from different members of said gyro means; means for apPlying each of said electrical signals from each member of said plurality of rate gyro means to the corresponding electro-hydraulic servo valve to obtain an output therefrom; means for applying the output of each of said plurality of electro-hydraulic servo valves to the corresponding rotary hydraulic actuator to obtain an output therefrom; and means for controlling output of each of said plurality of gyro means by means of the output from the corresponding rotary hydraulic actuator and thereby affecting the position of said stand.
 2. The platform of claim 1 wherein said electronic means further comprises a control and logic circuit.
 3. The platform of claim 2 wherein each of the rate gyro-electrohydraulic servo valve-rotary hydraulic actuator combination has a limit switch incorporated therein.
 4. The platform of claim 3 wherein each of said electro-hydraulic servo valves is adapted to respond to low frequency changes in the position of said platform.
 5. The platform of claim 4 wherein said electronic means further includes amplifiers and shaper circuits. 